Trends

Large Diameter Sapphire Supports LED Market Growth

Just as silicon is to microprocessors, sapphire forms the foundation for the growth of LEDs. In order to support substantial market growth anticipated with the worldwide adoption of LED-based lighting, the LED industry is looking to large diameter wafers that offer increased yield in LED chips. Improved chip yields from 6-inch and larger wafers will help drive down costs of an LED light bulb. While migration to high-quality, large-diameter sapphire wafers will help address the need for increased volume of LEDs to support demand.

For many years, two-inch and four-inch diameter sapphire wafers have been the standard for LED production. Now, LED manufacturers are moving to six-inch diameter wafers to increase the yield of LED chips made from each wafer. The larger wafers will yield greater numbers of LED chips. For example, it would take 100,000 two-inch wafers to yield the same amount of LEDs as 10,000 six-inch wafers. A six-inch wafer will produce approximately 12 times as many chips as compared to a two-inch wafer. Although the geometrical area increase is 9x, the decreased curvature of the larger sized wafer allows more LED chips to fit along the outer perimeter. This is called the “edge effect”— producing more chips than just the raw calculation of the geometrical area.

As the market matures, it is anticipated that eight- and 12-inch large diameter wafers will emerge as a desired choice for LED production. The high yield of large diameter sapphire wafers enables manufacturers to affordably produce the volumes of LEDs needed to support the adoption of solid state lighting.